The Reichsbürger movement has existed in Germany and beyond for decades, but a series of recent violent incidents and suspected plots is now creating more concern for Germany's security officials.
Investigators said on Wednesday that they were searching the homes of various people across Germany, suspected of plotting attacks against Jewish people, asylum seekers and police. According to DPA security sources, the group was formed by a so-called "Reichsbürger".
'The Federal Republic of Germany is illegitimate'
Since the 1980s, the movement has consisted of a loose association of fragmented groups across the country that agree more or less that the Federal Republic of Germany is not legitimate because they believe entities like the German Reich or even Prussia still exist.
Affiliates often circulate other conspiracy theories among themselves - such as that Germany is an American colony - and they are also often linked to right-wing extremism.
The leader of Germany's BfV domestic security agency told DPA on Wednesday that there are an estimated 10,000 Reichsbürger across the country, and about 500 to 600 of them are considered right-wing extremists.
But he also noted that the movement is diverse in their ideologies, with some creating their own communities rather than referring to a German Reich.
Why they have a problem with the police
Reichsbürger often come into confrontation with police because of their refusal to recognize German law, and often set up their own “governments”, forging their own forms of identification.
In 2014, one man tried to buy an AK-47 assault rifle using an identity card from the non-existent “Free State of Prussia”.
And then there's the self-proclaimed "King of Germany", Peter Fitzek, who has been accused of embezzling more than €1 million from his supporters. Fitzek established his own "kingdom" in 2012 on the grounds of a former hospital in Saxony-Anhalt.
The "kingdom" - which can be seen below on Google Maps - even has its own currency, bank and started distributing passports to its "citizens".
Police officer shot dead in Bavaria
But a similar confrontation in Bavaria between police and a Reichsbürger in October became deadly when police went to seize a man's guns and he opened fire, killing one officer.
Following the deadly encounter, it emerged that police were investigating possible members of the movement within their own ranks - a perhaps surprising twist that people charged with enforcing the law could also be part of a group that does not recognize laws.
But officers across the country have been subject to disciplinary procedures for their suspected links to the movement. And this week prosecutors said two high-ranking officers that worked with the policeman slain in October were in touch with his Reichsbürger shooter and might have been able to prevent their colleague's death.